path: root/fs/nfs/pagelist.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * linux/fs/nfs/pagelist.c
 *
 * A set of helper functions for managing NFS read and write requests.
 * The main purpose of these routines is to provide support for the
 * coalescing of several requests into a single RPC call.
 *
 * Copyright 2000, 2001 (c) Trond Myklebust <trond.myklebust@fys.uio.no>
 *
 */

#include <linux/slab.h>
#include <linux/file.h>
#include <linux/sched.h>
#include <linux/sunrpc/clnt.h>
#include <linux/nfs.h>
#include <linux/nfs3.h>
#include <linux/nfs4.h>
#include <linux/nfs_fs.h>
#include <linux/nfs_page.h>
#include <linux/nfs_mount.h>
#include <linux/export.h>
#include <linux/filelock.h>

#include "internal.h"
#include "pnfs.h"
#include "nfstrace.h"
#include "fscache.h"

#define NFSDBG_FACILITY		NFSDBG_PAGECACHE

static struct kmem_cache *nfs_page_cachep;
static const struct rpc_call_ops nfs_pgio_common_ops;

struct nfs_page_iter_page {
	const struct nfs_page *req;
	size_t count;
};

static void nfs_page_iter_page_init(struct nfs_page_iter_page *i,
				    const struct nfs_page *req)
{
	i->req = req;
	i->count = 0;
}

static void nfs_page_iter_page_advance(struct nfs_page_iter_page *i, size_t sz)
{
	const struct nfs_page *req = i->req;
	size_t tmp = i->count + sz;

	i->count = (tmp < req->wb_bytes) ? tmp : req->wb_bytes;
}

static struct page *nfs_page_iter_page_get(struct nfs_page_iter_page *i)
{
	const struct nfs_page *req = i->req;
	struct page *page;

	if (i->count != req->wb_bytes) {
		size_t base = i->count + req->wb_pgbase;
		size_t len = PAGE_SIZE - offset_in_page(base);

		page = nfs_page_to_page(req, base);
		nfs_page_iter_page_advance(i, len);
		return page;
	}
	return NULL;
}

static struct nfs_pgio_mirror *
nfs_pgio_get_mirror(struct nfs_pageio_descriptor *desc, u32 idx)
{
	if (desc->pg_ops->pg_get_mirror)
		return desc->pg_ops->pg_get_mirror(desc, idx);
	return &desc->pg_mirrors[0];
}

struct nfs_pgio_mirror *
nfs_pgio_current_mirror(struct nfs_pageio_descriptor *desc)
{
	return nfs_pgio_get_mirror(desc, desc->pg_mirror_idx);
}
EXPORT_SYMBOL_GPL(nfs_pgio_current_mirror);

static u32
nfs_pgio_set_current_mirror(struct nfs_pageio_descriptor *desc, u32 idx)
{
	if (desc->pg_ops->pg_set_mirror)
		return desc->pg_ops->pg_set_mirror(desc, idx);
	return desc->pg_mirror_idx;
}

void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
		       struct nfs_pgio_header *hdr,
		       void (*release)(struct nfs_pgio_header *hdr))
{
	struct nfs_pgio_mirror *mirror = nfs_pgio_current_mirror(desc);


	hdr->req = nfs_list_entry(mirror->pg_list.next);
	hdr->inode = desc->pg_inode;
	hdr->cred = nfs_req_openctx(hdr->req)->cred;
	hdr->io_start = req_offset(hdr->req);
	hdr->good_bytes = mirror->pg_count;
	hdr->io_completion = desc->pg_io_completion;
	hdr->dreq = desc->pg_dreq;
	nfs_netfs_set_pgio_header(hdr, desc);
	hdr->release = release;
	hdr->completion_ops = desc->pg_completion_ops;
	if (hdr->completion_ops->init_hdr)
		hdr->completion_ops->init_hdr(hdr);

	hdr->pgio_mirror_idx = desc->pg_mirror_idx;
}
EXPORT_SYMBOL_GPL(nfs_pgheader_init);

void nfs_set_pgio_error(struct nfs_pgio_header *hdr, int error, loff_t pos)
{
	unsigned int new = pos - hdr->io_start;

	trace_nfs_pgio_error(hdr, error, pos);
	if (hdr->good_bytes > new) {
		hdr->good_bytes = new;
		clear_bit(NFS_IOHDR_EOF, &hdr->flags);
		if (!test_and_set_bit(NFS_IOHDR_ERROR, &hdr->flags))
			hdr->error = error;
	}
}

static inline struct nfs_page *nfs_page_alloc(void)
{
	struct nfs_page *p =
		kmem_cache_zalloc(nfs_page_cachep, nfs_io_gfp_mask());
	if (p)
		INIT_LIST_HEAD(&p->wb_list);
	return p;
}

static inline void
nfs_page_free(struct nfs_page *p)
{
	kmem_cache_free(nfs_page_cachep, p);
}

/**
 * nfs_iocounter_wait - wait for i/o to complete
 * @l_ctx: nfs_lock_context with io_counter to use
 *
 * returns -ERESTARTSYS if interrupted by a fatal signal.
 * Otherwise returns 0 once the io_count hits 0.
 */
int
nfs_iocounter_wait(struct nfs_lock_context *l_ctx)
{
	return wait_var_event_killable(&l_ctx->io_count,
				       !atomic_read(&l_ctx->io_count));
}

/**
 * nfs_async_iocounter_wait - wait on a rpc_waitqueue for I/O
 * to complete
 * @task: the rpc_task that should wait
 * @l_ctx: nfs_lock_context with io_counter to check
 *
 * Returns true if there is outstanding I/O to wait on and the
 * task has been put to sleep.
 */
bool
nfs_async_iocounter_wait(struct rpc_task *task, struct nfs_lock_context *l_ctx)
{
	struct inode *inode = d_inode(l_ctx->open_context->dentry);
	bool ret = false;

	if (atomic_read(&l_ctx->io_count) > 0) {
		rpc_sleep_on(&NFS_SERVER(inode)->uoc_rpcwaitq, task, NULL);
		ret = true;
	}

	if (atomic_read(&l_ctx->io_count) == 0) {
		rpc_wake_up_queued_task(&NFS_SERVER(inode)->uoc_rpcwaitq, task);
		ret = false;
	}

	return ret;
}
EXPORT_SYMBOL_GPL(nfs_async_iocounter_wait);

/*
 * nfs_page_lock_head_request - page lock the head of the page group
 * @req: any member of the page group
 */
struct nfs_page *
nfs_page_group_lock_head(struct nfs_page *req)
{
	struct nfs_page *head = req->wb_head;

	while (!nfs_lock_request(head)) {
		int ret = nfs_wait_on_request(head);
		if (ret < 0)
			return ERR_PTR(ret);
	}
	if (head != req)
		kref_get(&head->wb_kref);
	return head;
}

/*
 * nfs_unroll_lo